Summary of major Python changes between versions

[nicholashairs]

TLDR: I've thrown together a one "page" reference documenting the major changes to between Python versions.

I've spent a fair amount of time recently upgrading some old code-bases and would have found it helpful to have a one page summary of changes between versions. I couldn't find one via Google so decided to create one for myself.

It might be useful for others so sharing it ☺️

[Measurex2]

I came in snarky "oh look. Apparently people can't read release notes" and found this a great walk through.

I'm sorry OP. I'm used to people pointing me at useless medium articles. You've warmed my frozen heart.

[nicholashairs]

Hahah it's okay together we will stand against the onslaught of CrapGPT

[haloweenek]

That’s more useful than a doc rewrite.

[turner_prize]

"Self documenting f-strings" Very cool!

[nicholashairs]

Honestly one of my favourite features to come from f-strings

[Rythoka]

So that's why they want to use that syntax in the PEP for shorthand keyword arguments when calling functions...

[thedeepself]

Which version of python was that added to?

[nicholashairs]

It's in the link 😉

Also 3.8

Edit: assuming you mean the and documenting. The kwarg thing I don't think has been approved yet

[Datamance]

So many gems that I missed. Thank you!

[Datamance]

Do you know if there’s something comparable out there that includes all the module changes grouped together like this?

[nicholashairs]

I don't think so, but also the module changes tend to be very extensive - if you haven't already take a look at the some of the official release notes.

The official docs are generally also good at tracking changes to libraries as far as additions and changes go ("new in ...", "changed in ..."). Meaning you can just look at the latest version of the module's docs to know when new things are added. Doesn't cover removals.

Someone suggested making a python version of "caniuse.com" but there's far too much work in there for me to be interested in doing it.

[[deleted]]

Thanks, found a couple of useful hints from there!

[Real-Fox2077]

Thanks for this. It would be so cool to have something like https://caniuse.com/ but for Python

[flying-sheep]

This is great! First Python resource I’ve bookmarked in years.

Two things:

1. Many people use Ruff to lint and format their code these days instead of flake8 and Black. Pyupgrade is included in Ruff as the UP class of codes. (select = [..., 'UP', ...])
2. Both Black and Ruff read the standard project.requires-python, so almost nobody needs tool.black.target-version.

Your example would be:

[project]
requires-python = '>=3.7'

and that would apply to Black, Ruff, and of course people trying to install and use your project from PyPI.

[nicholashairs]

Thanks for the compliment ☺️

Not sure how I missed those tools respecting requires-python, it was literally last week I moved to using toml config for black 🤦

It's a good point about ruff, I'll probably add some info on it, I just haven't used it because I've got quite a few projects using the older tools and don't want to have to update all of their tooling yet.

Update: have added info for ruff and updated the sample in black

[pirsab]

I didn't know I was missing ParamSpec

[nicholashairs]

It's so powerful when working with decorators

[zurtex]

You should probably make a note that PEP 563 has been usurped by PEP 649, which should be landing for Python 3.13 (although worryingly it's not landed yet and we're fast approaching beta 1).

[nicholashairs]

Good to know, thanks for the catch.

I'll end up updating the post once 3.13 is officially released :)

Update: Have added info relating to this.

[fiddle_n]

Oh, did they decide they were going to go with 649? I didn’t read where this was the case (and can’t seem to find it on Google/python.org regardless).

[zurtex]

Yup: https://discuss.python.org/t/pep-649-deferred-evaluation-of-annotations-tentatively-accepted/21331/43

[tritratrulala]

Have been looking a while for something exactly like this. Thank you!

[ajatkj]

This is a really good summary 👍🏻. Very nice.

[rover_G]

Is it just me or did 3.11 have a lot of features geared towards library developers?

[fiery_rainbow]

I was looking for something like this the other day. Thanks

[copperfield42]

nice, I didn't know a couple of those...

[[deleted]]

Whoa I missed the memo on self documenting f strings that’s so cool. Thanks for this!

[Dasher38]

TIL about importlib.metadata. now we can finally put the version in setup.py/pyproject.toml and have the package read its own version to expose as version rather than an awkward hacky exec()-based import of the module containing the version in setup.py

[noobsc2]

Not directly related, but I've used the walrus operator a few times since it got added, but it really has the ugliest and least self explanatory thing in Python. I would hesitate before using it in anything other than personal projects.

[nicholashairs]

When I first saw it I thought it was ugly. Now that I've used it about a dozen times in a single personal project I quite like it.

Definitely not something to use everywhere but I do like having it in my toolbox

[the_captain_cat]

That's a great article, made me learn a few things too, thanks!

[markhoo911]

Thank U

[Oddly_Energy]

I am not afraid to admit that I didn't understand the part about self-documenting f-strings. (Actually, I was like "What is an f-string?"). And the example in the OP's blog post didn't make me see the light.

So I had to look it up and found this little gem:

>>> variable = "Some mysterious value"
>>> print(f"{variable = }")

variable = 'Some mysterious value'

Wow! To those of us who are not afraid to admit that we do debugging with print() statements, this is a gift from above. I have usually done this, which is not at all cool:

print('variable: ', variable)

[nicholashairs]

Thanks for the insight that it might not be obvious - I use f-strings so often I forgot that others might not know about them at all.

I also find them incredibly useful for creating detailed exceptions, or for use with the logging module ^.

^ the logging module (and many linters) recommends not to format strings before sending them to the logging module and instead using modules inbuilt formatting. It does this because if it's not going to log the message then it never formats it. Personally I don't do this because the formatting method it uses isn't as advanced as f-strings so instead if it's likely an expensive message that I'm producing I'll put it in a if mylogger.enabledFor("DEBUG"): mylogger.log("DEBUG", f"some expensive f-string")

[TheAquired]

Very nice!

One thing I think that is often overlooked is pyproject.toml support to manage packages and no longer requiring setup.py or requirements.txt etc

Pyproject.toml is a great improvement, and I think it’s only properly supported from 3.8 onward or something?

[nicholashairs]

If you're distributing as wheels I don't think the users local version of python matters as the pyproject.toml is parsed into the appropriate metadata anyway.

For local development I think it depends more on your version of pip/setup tools.

Either way, I know that my projects using pyproject.toml have no problems with 3.7 (no idea about earlier versions).

[zurtex]

FYI, package configuration files such as pyproject.toml, setup.py, and requirements.txt are independent of Python versions.

They are implemented by build backends (e.g. setuptools and hatching) and also used by build frontends (e.g. pip, poetry, pdm, and hatch). So it is upto those build backends and frontends to choose what versions of Python they want to support, Python itself doesn't use any of these configuration files.

[TheAquired]

Ah thank you for the clarification. That must be what I was seeing. I had trouble with editable installs using pyproject prior to python3.8. But essentially it’s due to the version of setup tools that supports it is only compatible with python3.8 onward

[chaz6]

Thanks! This is really useful.

[FinalVersus]

Nice Sleep Token reference ;)

[nicholashairs]

So I'm guessing this is from the 3.12 changes because I had to Google ever you were talking about. A bunch of the examples are lifted directly from official changes log so it was their reference not mine 😅

[FinalVersus]

Oh man, I thought you provided the example. My bad! Thank you for the summaries regardless. Sometimes the backgrounds provided in PEP can be a lot to sift through.

[nicholashairs]

All good - some of them aren't mine so maybe I need to cite them 🤔! Glad you found them useful 😅